Follicular Lymphoma: An Indolent Malignancy That is Incurable. FL arises from a single mature B lymphocyte that has rearranged and expressed a unique set of immunoglobulin heavy and light chain variable region genes, but that also has rearranged and deregulated the expression of the BCL2 anti-apoptotic gene. We suspect that the immunoglobulin B cell receptor transmits growth and survival signals to the developing tumor clone, perhaps from an unidentified antigen stimulus. Through a series of further genetic changes a more malignant subclone can emerge that often results in the death of the patient. During a long indolent phase the tumor can respond to a variety of chemotherapy drugs, radiotherapy treatments and immunological therapies, such as monoclonal antibodies, but the disease is uniformly incurable. There is no suitable animal model for human FL and therefore our understanding of the biology of this malignant disease is necessarily restricted to an analysis of tumor specimens obtained from patients at various stages of the malignant progression.